According to the monitoring theory of consciousness, a mental state is conscious in virtue of being represented in the right way by a monitoring state. David Rosenthal, William Lycan, and Uriah Kriegel have developed three different influential versions of this theory. In order to explain colour experiences, each of these authors combines his version of the monitoring theory of consciousness with a specific account of colour representation. Even though Rosenthal, Lycan, and Kriegel disagree on the specifics, they all hold that colours are represented by a single type of mental state. The main goal of this paper is to show that a more complex account of colour representation is needed for the monitoring theory of consciousness to do justice to the phenomenology of colour experiences. In particular, I will argue that the fine-grained character of colour experience?that is, the fact that perceivers can become conscious of small differences between colours?requires that colour representation be construed in terms of two different types of mental states, namely sensory states that represent appearance properties and colour representations that represent physical colours